A novel biorecognition receptor Citropin-A modified impedimetric biosensor for detection of LNCaP prostate cancer cells.

In this study, Citropin-A (Cit-A) as a biorecognition receptor was used for the first time to develop electrochemical impedance spectroscopy (EIS) based biosensor for the detection of Lymph Node Carcinoma of the Prostate (LNCaP) cancer cells. The biosensor was engineered by modification of a gold electrode (AuE) with cysteamine (Cys), Poliamidoamin (PAMAM (G4)) dendrimers, avidin, and biotinylated Cit-A, respectively. The detection time of the LNCaP cells was determined as 300 s by chronoimpedance (CI). Chronoimpedance also provided an exact detection time to avoid non-specific adsorptions. The biosensor showed good linearity between 1500 cells/L and 12000 cells/L, limit of detection (LOD), and limit of quantification (LOQ) values were 518 cells/L and 1570 cells/L, respectively.

Using dynein heavy chain 5 and creatine kinase levels in cervical fluid and blood for early diagnosing of ectopic pregnancy.

AIM: Ectopic pregnancy is a life-threatening problem in reproductive ages. Diagnosing ectopic pregnancy in the early period provides to reducing mortality and morbidity and gives an opportunity for medical treatment to preserve fallopian tubes. Evaluation of cervical fluid for determining ectopic pregnancy with new promising markers provided different aspects for diagnosing ectopic pregnancy in the present study. METHODS: In this prospective clinical study, ectopic pregnant patients as ectopic pregnancy group (n = 46), intrauterine pregnant patients as intrauterine pregnancy group (n = 29) and not-pregnant patients as nonpregnancy group (n = 10) participated to study. Cervical fluid samples were collected with using merocel sponge. In addition, serum samples were obtained from patients. Dynein heavy chain 5 (DNAH5) and creatine kinase (CK) levels were determined by enzyme-linked immunosorbent assay kits in samples. RESULTS: Reduced cervical fluid DNAH5 levels was diagnosed in ectopic pregnancy group compared to intrauterine pregnancy group (median 3.42 ng/mL; 25-75% percentile 0-9.56 ng/mL vs median 6.14 ng/mL; 1.40-8.31 ng/mL; P < 0.001). On the other hand, DNAH5 protein was not detected in nonpregnant patients' samples. In addition, statistical significant increased cervical fluid CK levels were diagnosed in ectopic pregnancy group compared to intrauterine pregnancy group (median 4477.61 IU/L; 0-64 925.37 IU/L vs 0 IU/L; 0-6832.30 IU/L; P = 0.006). CONCLUSION: Measuring of CK and DNAH5 in cervical fluid could be promising markers for early diagnosing of ectopic pregnancy. Decreased DNAH5 levels in cervical fluid might be result from abnormal cilia function in ectopic pregnant patients. ClinicalTrials.gov ID. NCT02995356.

Fullerene-PAMAM(G5) composite modified impedimetric biosensor to detect Fetuin-A in real blood samples.

The aim of this study is to develop a nanomaterial-dendrimer composite modified biosensor to detect Fetuin-A (HFA) in real blood samples. For this purpose, we designed an Electrochemical Impedance Spectroscopy (EIS) based anti-Fetuin-A (Anti-HFA) modified biosensor system and tested in real blood samples. Chronoimpedance was also employed. The same samples were analyzed with ELISA and the results were compared for validation of the new system. Gold screen printed electrodes (AuSPE) were used as transducer. Firstly, a self-assembly monolayer (SAM) was formed on gold surface by 4-aminothiophenol (4-ATP), Fullerene and PAMAM-NH2 (G5), layers were formed, consecutively. Then Anti-HFA was immobilized on Au/4-ATP/Fullerene/PAMAM electrode via glutaraldehyde. The chronoimpedance test was employed to investigate the optimum analysis duration. According to the data of chronoimpedance, the total analysis time for EIS was chosen as 3 min. The new biosensor was compared with the ELISA method which required 150 min. The calibration curve was prepared electron transfer resistance of the electrode (ΔRet) per minute as ohm and 1.66-134 ng/mL.min with a R2 = 0.9912. The LOD and LOQ of the biosensor was calculated as 0.48 ng/mL.min, 1.46 ng/mL.min, respectively. Linear regression analysis indicated that the novel developed biosensor results agreed well with that of the conventional ELISA assay.

Impedimetric antimicrobial peptide biosensor for the detection of human immunodeficiency virus envelope protein gp120.

This study presents the design and implementation of an antimicrobial peptide-based electrochemical impedance spectroscopy (EIS) based biosensor system. The biosensor consists of a gold coated carbon electrode with MXene and silver nanoparticles (AgNPs) for the label-free detection of the human immunodeficiency virus (HIV) envelope protein gp120. Scanning electron microscopy was used to confirm the presence and distribution of MXene and AgNPs on the biosensor surface. The employment of the antimicrobial peptide on the electrode surface minimized the denaturation of the biorecognition receptor to ensure reliable and stable performance. The biosensor exhibited a linear range of 10-4000 pg mL-1 for gp120 detection, demonstrating good repeatability in real samples. The limit of detection (LOD) and limit of quantification (LOQ) were also calculated as 0.05 pg mL-1 and 0.14 pg mL-1, respectively. This biosensing platform has promising applications in the detection of HIV in clinical and point-of-care settings.

Sensitive Detection of Perfluoroalkyl Substances Using MXene-AgNP-Based Electrochemical Sensors.

Per- and polyfluoroalkyl substances (PFAS) pose a significant threat to the environment due to their persistence, ability to bioaccumulate, and harmful effects. Methods to quantify PFAS rapidly and effectively are essential to analyze and track contamination, but measuring PFAS down to the ultralow regulatory levels is extremely challenging. Here, we describe the development of a low-cost sensor that can measure a representative PFAS, perfluorooctanesulfonic acid (PFOS), at the parts per quadrillion (ppq) level within 5 min. The method combines the ability of PFOS to bind to silver nanoparticles (AgNPs) embedded within a fluorine-rich Ti3C2-based multilayered MXene, which provides a large surface area and accessible binding sites for direct impedimetric detection. Fundamentally, we show that MXene-AgNPs are capable of binding PFOS and other long-chain PFAS compounds, though the synergistic action of AgNPs and MXenes via electrostatic and F-F interactions. This binding induced concentration-dependent changes in the charge-transfer resistance, enabling rapid and direct quantification with extremely high sensitivity and no response to interferences. The sensor displayed a linear range from 50 ppq to 1.6 ppt (parts per trillion) with an impressively low limit of detection of 33 ppq and a limit of quantification of 99 ppq, making this sensor a promising candidate for low-cost screening of the PFAS content in water samples, using a simple and inexpensive procedure.

An impedimetric vascular endothelial growth factor biosensor-based PAMAM/cysteamine-modified gold electrode for monitoring of tumor growth.

In the present work, we have developed a new biosensor based on fourth-generation (G4) PAMAM dendrimers for the analysis of vascular endothelial growth factor (VEGF). First, the PAMAM dendrimers were covalently attached to a cysteamine-modified Au electrode by glutaraldehyde. With the help of the amino groups located on its surface, vascular endothelial growth factor receptor-1 (VEGF-R1) was immobilized via glutaraldehyde cross-linking. VEGF-R1 loading was investigated to identify the optimal VEGF-R1 immobilization conditions for the best sensitivity of the new biosensor. In addition, Kramers-Kronig transforms were also analyzed for immobilization and measurement processes. The biosensor had a linear range of 5 to 125 pg/mL VEGF. The fabricated biosensor had good repeatability and reproducibility. Finally, the results for artificial serum samples measured by the present biosensor showed a good recovery for VEGF detection.

Emerging Applications of Electrochemical Impedance Spectroscopy in Tear Film Analysis.

Human tear film, with a flow rate of 1-3 µL/min, is a rich bodily fluid that transmits a variety of metabolites and hormones containing proteins, lipids and electrolytes that provide clues about ocular and systemic diseases. Analysis of disease biomarkers such as proteins, mRNA, enzymes and cytokines in the tear film, collected by noninvasive methods, can provide significant results for sustaining a predictive, preventive and personalized medicine regarding various diseases such as glaucoma, diabetic retinopathy, keratoconus, dry eye, cancer, Alzheimer's disease, Parkinson's disease and COVID-19. Electrochemical impedance spectroscopy (EIS) offers a powerful technique for analyzing these biomarkers. EIS detects electrical equivalent circuit parameters related to biorecognition of receptor-analyte interactions on the electrode surface. This method is advantageous as it performs a label-free detection and allows the detection of non-electroactive compounds that cannot be detected by direct electron transfer, such as hormones and some proteins. Here, we review the opportunities regarding the integration of EIS into tear fluid sampling approaches.

State-of-the-art Hepatocellular Carcinoma Biomarker Detection by Biosensor Technology-a Review.

Biosensors have become a very interesting field in recent years, thanks to their potential to be converted into self-diagnostic technologies. Being able to analyze a biomarker with different biosensor systems has great potential. This potential is important in terms of time, cost, and practicality with its use in the analysis of difficult-to-diagnose diseases in clinical studies. In this review, the biosensors used in the determination of hepatocellular carcinoma (HCC) biomarkers were compiled. Electrochemical, optical, and piezoelectric biosensors used in the analysis of proteins, DNA, RNA, and cells with varying concentrations in HCC can be designed based on antibodies, nanocomposites, DNA, and aptamers.

Label-free highly sensitive detection of DNA approximate length and concentration by impedimetric CRISPR-dCas9 based biosensor technology.

In this study, we designed a CRISPR-dCas9-based biosensor with potential clinical use in glioblastoma subtype discrimination through detection of isocitrate dehydrogenase R132H (IDH) mutation status. The electrode was modified to detect mutant DNA cysteamine (Cys), PAMAM, dCas9 and sgRNA for R132H mutations, respectively. The biosensor system we proposed was able not only to detect mutant DNA, but also to measure the approximate length of DNA. Therefore, it can be considered that the biosensor technology that we developed is novel in the field of DNA biosensors. Another superior capability of the biosensor system is that it can simultaneously measure DNA concentration by electrochemical impedance spectroscopy and DNA length by capacitive detection, which lowers the concentration-based false-positive signals. The calibration range was obtained between 100 fM and 1000 fM, LOD and LOQ were also calculated as 33.96 fM and 102.91 fM respectively. Moreover, thanks to the sensitivity of the capacitive detection, the biosensor was able to discriminate the same EIS signals of the 200 bp and 250 fM concentration data and 1000 bp and 50 fM concentration data. In conclusion, the biosensor was capable of detect target DNA and DNA length, simultaneously in minutes.

Digital Diagnostics and Mobile Health in Laboratory Medicine: An International Federation of Clinical Chemistry and Laboratory Medicine Survey on Current Practice and Future Perspectives.

BACKGROUND: A survey of IFCC members was conducted to determine current and future perspectives on digital innovations within laboratory medicine and healthcare sectors. METHODS: Questions focused on the relevance of digital diagnostic solutions, implementation and barriers to adopting digital technologies, and supplier roles in supporting innovation. Digital diagnostic market segments were defined by solution recipient (laboratory, clinician, patient/consumer, payor) and proximity to core laboratory operations. RESULTS: Digital solutions were of active interest for >90% of respondents. Although solutions to improve core operations were ranked as the most relevant currently, a future shift to technologies beyond core laboratory expertise is expected. A key area of potential differentiation for laboratory customers was clinical decision support. Currently, laboratories collaborate strongly with suppliers of laboratory integration software and information systems, with high expectations for future collaboration in clinical decision support, disease self-management, and population health management. Asia Pacific countries attributed greater importance to adopting digital solutions than those in other regions. Financial burden was the most commonly cited challenge in implementing digital solutions. CONCLUSIONS: Specialists in laboratory medicine are proactively approaching digital innovations and transformation, and there is high enthusiasm and expectation for further collaboration with suppliers and healthcare professionals beyond current core laboratory expertise.

CRISPR-dCas9 powered impedimetric biosensor for label-free detection of circulating tumor DNAs.

Label-free biosensors which can be integrated into lab-on-a-chip platforms have the advantage of using small volumes for rapid and inexpensive measurements contrary to label-based technologies which are often more costly and time-consuming. In this study, graphene oxide screen printed electrodes (GPHOXE) were modified by deactivated Cas9 (dCas9) proteins and synthetic guide RNA (sgRNA) as the biorecognition receptor for label-free detection of circulating tumor DNAs (ctDNA). This was achieved by detection of a tumor related mutation (PIK3CA exon 9 mutation) via sequence-specific recognition followed by electrochemical impedance spectroscopy (EIS) analysis. The biosensor showed high specificity as there was no impedance signal for other ctDNA sequences, even the single nucleotide mismatch. dCas9-sgRNA modified biosensor demonstrated linear detection limits between 2 and 20 nM for 120 bp ctDNA's in 40 s. The calibration curve showed good linearity, LOD was calculated as 0.65 nM and LOQ was calculated as 1.92 nM. Selectivity and repeatability studies were carried out in real blood samples and the recovery was higher than 96%. In conclusion, dCas9-sgRNA was effectively immobilized and optimized on GPHOXE as the selective biorecognition receptor of this ultrafast impedimetric biosensor. The CRISPR-dCas9 powered impedimetric system showed good selectivity, high repeatability and good recovery properties. This is the first literature to report the use of CRISPR/Cas technology as a label-free tool that can be used in an impedimetric system for detection of ctDNA's.

Non-invasive cortisol detection in saliva by using molecularly cortisol imprinted fullerene-acrylamide modified screen printed electrodes.

In this study, we developed an impedimetric sensor system by using molecularly cortisol imprinted acrylamide polymers on fullerene modified carbon electrode to detect cortisol in real saliva samples. The polymer layer was formed on fullerene modified screen printed carbon electrodes with the ratio of 1:2 (cortisol:acrylamide) and ammonium persulfate (APS) was used as the initiator of polymerization. The sensor surface was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Scanning Electron Microscopy (SEM). Performances of the electrode were determined as follows; calibration curve was calculated between 0.5 nM and 64 nM, R2 = 0.9939, LOD and LOQ were 0.14 nM and 0.44 nM, respectively. Real human saliva samples were obtained from 15 participants between 25 and 32 ages regardless of gender. The samples, which were collected at least 30 min after waking up and the new sensor method analysis were compared tandem mass spectroscopy coupled liquid chromatography system (LC-MS/MS). The sensor analysis showed a significant correlation with LC-MS/MS results (R2 = 0.9727).

A novel, ultra sensible biosensor built by layer-by-layer covalent attachment of a receptor for diagnosis of tumor growth.

In the presented research, a novel, ultra sensitive biosensor for the impedimetric detection of vascular endothelial growth factor (VEGF) is introduced. The human vascular endothelial growth factor receptor 1 (VEGF-R1, Flt-1) was used as a biorecognition element for the first time. The immobilization of VEGF-R1 on glassy carbon electrodes was carried out using layer-by-layer covalent attachment of VEGF-R1. The electrochemical properties of the layers constructed on the electrodes were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The differences in electron transfer resistance (R(et)) between the working solution and the biosensor surface, recorded by the redox probe K(3)[Fe(CN)(6)]/K(4)[Fe(CN)(6)], confirmed the binding of VEGF to VEGF-R1. The new biosensor allowed a detection limit of 100 fg mL(-1) with a linear range of 100-600 fg mL(-1) to be obtained. The biosensor also exhibited good repeatability (with a correlation coefficient of 1.95%), and reproducibility.